Abstract: Under the same heat input and similar chemical composition of welding wire, the MAG welding tests of cable wire with diameter of 2.4 mm and solid wire with diameter of 1.2 mm were carried out. The microstructure and grain size of the cable wire welded joint was compared and analyzed, and the mechanical properties of the welded joints were analyzed.The results show that the arc force and plasma flow force of cable wire MAG welding are smaller, therefore the depth-width ratio of the weld is smaller than that of solid wire welding.Because of the characteristics of arc rotation and stirring pool, the cable welding wire joint has fine grains and more uniform structure, and the grain size of weld zone, fusion zone and heat affected zone is smaller than that of solid welding wire.The tensile property, impact property and side bending property of the MAG joint welded by cable wire are better than those of the MAG joint welded by solid wire.